Method of making indicating instruments



O. SIEPER METHOD OF MAKING INDIGATING INSTRUMENTS Dec. 22, 1931.

Filed Feb. 2. 1927 w---ww l l l ll INVENTOR OTr'o 5/.5 PER BYM$M ATTORNEY Patented Dec. 22,r 1931 UNM-aul STATES PATENT OFFICE OTTO SIEPER, OF RICHMOND HIIL, NEW YORK, ASSIGNOR, BY MESN ASSIGNMENTS, T0 MOTO METER GAUGE &, EQUIPMENT CORPORATION, OF LONG ISLAND CITY,V NEW YORK, A CORPORATION OF DELAWARE METHOD OF MAKING INDICATING INSTRUMENTS n Application 'led February 2, 1927. Serial No. 165,300.

rlhis invention has to do with soldering or brazing, and particularly with controlling the temperature of the body 4or bodies being Worked on where the usual soldering or braZ- ing temperature would be apt to result in injury to desired properties of the bodies.

More particularly, and as illustrated in the present'application, the invention has to do with the soldering or brazing of the filling tube and the pressure transmitting capillary tube to the Bourdon coil of a distance type thermometer or other pressure operated instrument. The Bourdon coil of such an instrument, after being joined to the capillary pressure transmitting tube and to the filling tube, is Ysoldered by means of a soft solder to the frame by which theV instrument movement is carried.V It has been the practice heretofore to use soft solder for each of these successive soldering operations. Under such circumstances it has frequently happened that the first solder applied inruniting the Bourdoncoil with the filling and pressure tubes has been fused and caused to flow at the second soldering operation with the result that the jointbetween the Bourdon coil and said tubes has been unsealed, or that the end of said tubes or one of them has been closed by the solder','malring it impossible to complete the m strument.

In accordance with they present invention, this diiiculty is overceme ybyA using a hard solder having a yrelatively high melt-ing point for thefirst soldering operation and the usual soft solder for the second. For example, a high melting solder, such as a silver solder,

is desirably employed for uniting the Bour-` don coil with the4 pressure transmitting and filling tubes, and a relatively low melting solder is employed' for subsequently uniting the Bourdon coil with the instrument frame. By the adoption of this'practice a workman of ordinary skillis enabled to perform the second soldering operation without any sub`` stantial danger ofinjuriously affecting the work accomplished at the first solderingoperation. I

The use of hardsolder for uniting the Bourdon coil with the pressure transmitting anufacture of an operative in` and filling tubes is also highly desirable for i y the reason that it effects a much stronger and more durable joint and a more permanent seal than the soft solders heretofore employed `for the purpose.

The useof such a solder has not been practicable heretofore, however, for the reason that thehigh soldering temperature required would cause the Bourdon coil to be heated to suoli an extent thatl the temper of a considerable portion of the coil, of indefinite length, would be changed and rendered stiff and therefore not responsive tothe desired extent to variations of pressure within it. t

' AIt is an important object of the present in- Vention to enable the superior type of joint obtainable by the use of hard solder to be effected between the Bourdon c oil and the pressure transmitting and filling tubes,- without injuriously affecting the Bourdon'coiL Tothis end provision is desirably made of a heat dissipating holder in which the end of the Bourdon. coil is held during soldering, and which the flexible part of the Bourdon coil is positively guarded against injurious overheating.

In the illustrative embodiment of the in` vention, such holder consists of cooperating metallic jaws vhaving'passagesfor the circulation of cooling watertherethrough, but it will be understood that the invention is not confined in its broader aspects `to` the employment of' any particular cooling medium or to theprovision of any kcirculatory system at all, it'being necessary only that the clamp shall have a capacity for absorbing or dissipating heat suiiicient to prevent the transmission of heat to an injurious degree to the flexible part of the Bourdon coil.

Other objects and advantages willhereinafter appear. i

In the drawings vforming a part of' this specification: y n Y Figure l is a plan view ofa clamp embodying features ofthe present invention;

Figure 2 is a side elevation of said clamp;

Figure 3 is a vertical, sectional viewr through the clamp on the line 3-.3 of Figure l, looking in the direction of the arrows;

Figure 4 is a horizontal view on th'e'fline 4 4 of'Figure 2 looking in the direction of the arrows;

Figure 5 is a fragmentary, vertical section on an enlarged scale through an end of the Bourdon tube showing how the connected tubes are fitted therein; and n Y Figure 6 is a diagrammatic, plan view showing how the Bourdon coil is soldered to the instrument vframev substantially at its junction with the tubes 1 and 2.

In the illustrative embodiment of the invention novel mechanism is used for brazing the capillary tube 1 and the Vfilling tube 2 toV a Bourdon tube 3. This brazing operation is ing instruments, granted April 28, 1931.

Y As has been pointed out above, it has been impracticable'heretofore to braze the` tubes 1 and 2 to the Bourdon tube 3 because,l by methods heretofore known, the high temperature required for brazing would cause such excessive heating of the Bourdon tube that the desired temper of a portion of the tube would be destroyed, so that uniformity in the finished instruments could not be maintained. Y y

In accordance with the present invention the brazing heat is controlled and dissipated without permitting the Bourdon tube to be injuriously affected. A bracket 4l fixed on a work table rigidly supports va jaw 6 of a clamp 7 in which the Boudon tube isfheld during brazing. The clamp 7 comprises a second jaw 8 connected to the jaw 6 by a hinge' 9. The jaws 6 andr 8 have complementary recesses 10 and 11 which,lwhen the jaws are brought together, form a passage between them of a shape and size to closely lit the Bourdon tube. The jaws 6' and 8 are provided with bores or passages through which cooling water is caused to circulate for controlling the temperature of the clamp and carrying offk the heat transmitted to the clamp from the Bourdontube.

kA water supply pipe-12 is connected to 'a lower passage 13 in the jaw 6 Yand cornmunicates at its forward end with an upwardly extending, vertical passage 14 which runs alongside the recess 10. The passagel/l communicates at its upper end with an upper horizontal passage 15 which, in

turn,.is connected through a pipe 16, a flexible tube 17, and a Vsecond pipe 18 with an upper horizontal passage 19 in the movablev jaw. The passage V19 communicates with a downwardly extending passage 20 alongside the recess11 and the passage 20 in turn lets into a rearwardly extend-v V ing, horizontal passage 21 in the lower part of the movable jaw 8. The passage 21 communicates at its rear end with a water discharge pipe 22. F rom the foregoing description it will be seen that the water entering the clamp from pipe 12 first flows through the passages of the liXedjaw 6, then through the passages of the movable jaw 8, and then through the discharge pipe 22. The pipe 12 may V be connected to an vordinary water faucet and therate offlow may be regulated to maintain the clamp and the Bourdon tube held thereby at the temperature desired.

The described passages through the jaws 6' and 8 may be bored therein and the ends of the passages may be closed by suitable plugs, Vas 22a, indicated in dotted lines in Figures 1 and 2.

An I-bolt 23 extends through a small bore 24 and a large bore 25 of the movable clamp jaw 8, and is threaded into the lixed clamp jaw 6. An operating member 26 comprising a cam or eccentric 27 and a handle 28, and pivoted on the I-bolt 23 by means of a bearing screw 29, may be swung in one direction to press the movable jaw 8 into i'irm clamping engagement with the xed jaw 6, and may-be moved in the opposite direction to release such clamping pressure. A coil compression spring 30 in the large bore 25 of the movable jaw 8 acts to force the jaws apart as soon as the clamping pressure of the operating member 26 is released.

In the use o f theV device the lBourdon tube 3 is placed in the recesses l10 and 11 of the ljaws 6A and 8 withits upper end extending a short distance above said jaws. The operating member v26 is then swung to clamp the Bourdon tube in the jaws. The tubes 1 and 2 are then'setin the end of the'Bourdon tube and brazed thereto. The jaws are then opened and the operation described is repeated upon other pieces of work.

It is a feature of the described clamp that it is capable of dissipating the brazing heat fast enough to enable the clamp to be used continuously without any interruption for cooling of the clamp between operations. Such capacity is not necessary to the pracicing of the invention, however, since the primary object. of the invention would be attained by any means capable of enabling l.a singlebrazing operation to be performed without injuriously affecting the work. Y While I have illustrated and described in detail certain preferred forms of my invention, it is to be understood that changes may be made therein and the invention'embodied in other structures. I do not, therefore, desire to limit myself to the specific constructions illustrated,1but intend to cover my invention broadlyin whatever `form its principle may be utilized.

I claim: l

1. The method of making pressure Yoperated instruments Which comprises providing an instrument frame, a Bourdon tube, and a pressure transmitting tube, brazing the pressure transmitting tube to an end of the Bourdon tube While protecting the Bourdon tube except said end portion thereof against overheating and thereafter soldering such end portion of the Bourdon tube rigidly to the instrument frame by means of soft solder.

2. The method of making pressure operated instruments which comprises providing an instrument frame, a Bourdon tube, and a pressure transmitting tube, brazing the pressure transmittting tube to the Bourdon tube While protecting the Bourdon tube except an end portion thereof against overheating, and thereafter securing such end portion of the Bourdon tube rigidly to the instrument frame.

3. The method of making pressure operated instruments which comprises providing an instrument frame, a Bourdon tube, and a pressure transmitting tube, holding the Bourdon tube in a heat dissipating holder with one end of the Bourdon tube proj eoting beyond the holder, bringing the pressure transmitting tube in contact With the projeoting end of the Bourdon tube, applying heat to the area of Contact and brazing said tubes together While maintaining all but said projecting end of the Bourdon tube below a predetermined temperature, and thereafter securing said end of the Bourdon tube to the instrument frame.

In testimony whereof I have aiiixed myl signature to this specication.

OTTO SIEPER. 

